1. Field of the Invention
The present invention relates to power supply circuits, and particularly to an energy saving power supply circuit.
2. Description of Related Art
Nowadays, with the earth's resources being depleted day by day, the cost of investment for energy increases significantly. Solar energy has drawn great attention from the energy industry as an alternative source of energy, and has found widespread applications in a variety of fields. For example, solar powered street-lamps are used in many countries.
A conventional solar powered street-lamp typically includes a solar energy operated absorption board, a storage battery, and a lamp. The solar energy operated absorption board absorbs solar energy and converts it into electric energy, which is used to recharge the storage battery. The storage battery supplies power to the lamp. However, the lamp typically works at a constant maximum power as supplied by the storage battery. Therefore, the lamp consumes energy quickly, so that the storage battery may not supply enough power to the lamp all night long.
What is desired, therefore, is to provide a power supply circuit which can effectively save electricity.